The use of processed, or granulated, cellulosic materials in animal litter is well known. For example, U.S. Pat. No. 4,374,794 to Kok illustrates a process for generating cellulosic cat litter pellets from fibrous waste sludge of the pulp and paper industries. U.S. Pat. No. 4,621,011 to Fleischer et al. also describes a process for making cellulosic granules and indicates their use in cat and other animal litter.
Given the relative abundance of suitable cellulosic source material, including waste paper, cellulosic granules could be a cost-effective alternative to clay granules. In commercial practice however, the use of cellulosic granules in conventional animal litter formulations has been limited because the cellulosic granules do not provide some of the consumer-demanded features provided by clay materials. In particular, conventional animal litters made up of substantial portions of cellulosic granules do not agglomerate or clump upon contact with aqueous liquids such as urine with or without conventional clumping agents.
As described in U.S. Pat. No. 5,101,771 to Goss, a clumping feature is highly desirable because it allows separation and removal of urine-soaked litter granules from an otherwise fresh bed of animal litter. Also referred to as scoopable litter because of a sieving scoop used to remove spent granules, such clumpable animal litter spares animal owners the expense and effort of full litter replacement.
Thus, there continues to be a need for a cellulosic animal litter that provides the urine clumping feature available from clay-based litters.